| Because China has a vast territory,a complex and diverse topographic structure,there are regional differences in the effects of climate warming on agricultural production.Understanding how climate change affects the effective accumulated temperature required by crops is the primary prerequisite for agricultural production to respond to global warming.In this paper,the penalty maximum F test is used to test the heterogeneity of the site temperature set and make interpolation correction.The best combination of historical data set and interpolation method is determined by Taylor diagram and best model for simulating effective accumulated temperature of China in cmip6 is so do.The method of Mann Kendall test,REOF,K-means cluster analysis is used to analyze the spatial distribution,time change,change before and after mutation and physical division of effective accumulated temperature required by rice,wheat,and corn in 1961-2017.And we predict what impact will globally warming of 1.5 ? and 2 ? have on China's food crop heat resources the thermal resources of China's grain crops in the future scenario.The purpose of this study is to fully understand the spatiotemporal pattern and long-term trends of agricultural heat resources in China,to help growers make better long-term decisions,and to provide theoretical basis and scientific support for the updating of national comprehensive agricultural zoning.The research mainly draws the following conclusions:(1)From 1961 to 2017,the effective accumulated temperature of rice,corn and wheat showed the zonal distribution law of changing with latitude from south to North and the ladder distribution law of changing with altitude from east to west.The largest area of wheat can be planted in China,followed by rice and corn.The effective accumulated temperature of three crops showed a significant increasing trend,among which wheat had the largest increase(about 40-90?·d/10a),followed by corn,rice had a small increase.The main area showing a decreasing trend was the middle reaches of Lancang River.The effective accumulated temperature of the three crops changed suddenly from 1991 to 2005.Before and after the change,the accumulated temperature boundary of the three crops showed a significant trend of northward and westward movement.In addition to the Qinghai Tibet Plateau,about 80% of China's regions have an increase in accumulated temperature of 100-300?·d for rice and corn,and 150-350?·d for wheat.The effective accumulated temperature of the three crops shows that the overall increase in the north is higher than that in the south.(2)Using the method of REOF and K-means cluster analysis to divide three crops.Rice accumulated temperature is divided into 5 zones,corn accumulated temperature has 4 zones and wheat accumulated temperature has 7 zones.Comparing the results of three crops,it is found that the results of rice and maize are similar;the high value region of three crops and the Yangtze River basin can be a separate region.In addition,there are two sub regions with Daliang Mountain as the boundary,and the regional division is reasonable and objective.(3)Under four different shared socio-economic paths(SSP),when the global temperature rises by 1.5 ? and 2 ?,the effective accumulated temperature of the three crops still shows the zonal distribution law changing with latitude from south to North and the ladder distribution law changing with altitude from east to west.The effective accumulated temperature showed an upward trend,all kinds of plant boundaries moved to the north,West and high altitude,and the increase of accumulated temperature in the 2 ? scenario was higher than that in the 1.5 ? scenario overall.The increase of accumulated temperature under the scenarios of SSP3-7.0 and SSP5-8.5 is relatively high,but the change trends of accumulated temperature of the three crops are inconsistent.The change results are complex,and there is no unified increase or decrease trend.The change trend of accumulated temperature of three crops under the scenarios of SSP1-2.6 and SSP2-4.5 is the same,and the development of human society under the two scenarios is relatively optimistic.(4)Under the ssp1-2.6 scenario,the global average temperature will rise to 1.5 ? in 2017 and 2.0 ? in 2034.Under the 1.5 ? scenario,the increase of accumulated temperature of three crops in about 60% of the country is 100-600?·d,and the increase of accumulated temperature of three crops in the northern region is higher than that in the southern region as a whole;under the 2 ? scenario,the increase of accumulated temperature in about 60% of the region is 250-900?·d,and the increase of accumulated temperature in the northern region is lower than that in the southern region as a whole.Under the ssp2-4.5 scenario,the global average temperature will rise to 1.5 ? in 2023 and 2.0 ? in 2038.Under the 1.5 ? scenario,the increase of accumulated temperature of three crops in about 60% of the country is about 100-700?·d;under the 2 ? scenario,the increase of accumulated temperature of about 60% of the country is about 250-800?·d;under the two scenarios,the increase of accumulated temperature of three crops in the west is higher than that in the Middle East. |
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